Hydraulically controlled adjustable back rest for seats and chairs



H. M. MOFADDEN 2,581,197 HYDRAULTCALLY ooNTRoLLED ADJUSTABLE BACK REST FOR SEATS AND CHAIRS Filed Sept. 24. 1947 Jan. 1, 1952 Yana. w14 d www Q u A TTOR E Y.

Patented Jan. 1, 1952 HYDRAULICALLY CONTROLLED ADJUST- ABLE BACK REST :Fon disnlrrs AND- 4CHAIRS Harry M. McFadden, Wichita, K ans.assignor.to -BoeingAirplane Company, Wichita, Kans.

Application September 24, 1947, Serial No. '175;8-51V i4 Claims. (Cl. 155-159.r)

'This "invention relates to seats and chairshav ing' adjustable Jback rests, and to hydraulic means for controlling the adjustment of the Yhack rests.

I am full-y aware that hydraulic means have previously been used to control the adjustment of seat `back rests, "but noone has to my knowledge produced a hydraulic control mechanism which 'isequivalent Ito my invention, -nor has anyone Vmounted and connected such a mechanism to the seat i-n the `manner contemplated by the present invention.

`It is -generally agreed `among the manufacturers of -seats ywith `adjustable backs that the most vpractical and convenient location Ifor the element which actually controls the back rest holding mechanism is on -'the arm of -the seat. Heretofore, `the location of this control element on the seat arm `:has necessitated a complicated linkage -for transmitting control element movement from the seat arm to the actual back rest 'holding mechanism, which has always been located beneath or within the seat bottom. This location of the holding mechanism has alsoecreated diiculties in that the back rest is usually hinged at its lower end to the seat, and an extension of the back rest below the hinge point has ordinarily been required to allow the holding mechanism proper leverage for back rest control.

These and other difficulties are obviated by Ymy invention which, briefly, involves the lccag.

tion of -a new type hydraulic back rest holding mechanism `inside the `arm of the seat, and in using `the zmechanism itself to `connect the stationary portionof the seat to the kadjustable back rest. Such location also permits the user oper- 4It is another object to provide aseat or this type in which the back rest 'holding mechanism and the user 4operated control element therefor are assembled as a single unit housedbythe seat arm. Y

It is a 'further object 5to Vprovide a lunit of this type which may `be removed -from the seat `for .repair or replacement-by the prior @removal of a single stud connectingthe Aunit to .the back rest. It is still a further object ofthe invention to provide '-a `novel hydraulic mechanism for -ho'ld- .2V ingaa seat :back rest. .in ny desired angle orinclnation with lrelation Lto the seat bottom. f

Another :Objectis to. provide .a hydraulicmech lanism -o'f this type 'which will automatically re- .turn the .seat back to a neutral vposition after the :user leaves theseat, thus providing identical angles of inclination for grouped unoccupied seatsorchairs.

These and .other objects A'of rthe invention `will fbe `clearly lunderstood when .the following `Vdescription is `read yin connection with the accompanying drawings, which are provided for illus- `trativepurposes only,.=and 'in which:

Figure 'l is a perspective View .of avehicle seat constructed in accordance iwith one v:embodiment of .this invention.

Figure l2 is a iside yelevation, partly -in vertical section, showing the details of construction of a hydraulic Vback A'rest holding mechanism constructed in 4accordance with `the invention, and also showing its manner of attachment to parts ofthe seat;

Figure 3 -is -a fragmentary view of certain parts of the `mechanism 'illustrated in Figure 1, some par-ts being-shown in section; and

Fig-urel is an exploded perspective view `of the hydraulic lback `rest 'holding mechanism and the two parts of its housing, which together lform alunitary-seat-arm.

Figure -1 illustrates one `embodiment of the invention. I-t will be understood that 'the invention is capable -of embodiment in various types of sea-ts -andchairs, although the `*seat chosen for illustration is of the 'aircraft type. Its frame structure comprises a lseat Vbase or bottom I0 which includes two rigid upright arm supports "H- and l2 located at its opposite sides, Yand two rigid back :rest frames I3 and It, the lower ends of Awhich -are respectively hinged to the seat bottom, as shown, to permit the back rest to tilt.

The hydraulic "units i5, which serve' to'holt the' individual back rests iat vvarious desired angles ci inclination 4with relation to the seat-bottom are illustrated in Figures '2, v3, and-4. Referring to'Figurelsucha hydraulic unit includes -a housing vthe major portion of which is in the form vof acylinder t6.

The remaining portion I1 of this housing attaches to the cylinder, as shown, and is suitably shaped lto facili-tate the VApivotal attachment `of its freeend to theseat back, the end being shown curved, flattened, and perforated in this "in--Y stance, to receive a ypivot pin or bolt 60, which anchors to thelback lres-t.

The cylinder I 6 houses a piston made up of two threadedly connected parts I8 and I9. The piston section I8 includes a concentric tubular valve stem housing which also serves as a piston rod. A packing gland 2I closes one end of the cylinder and permits reciprocation of the piston rod 20 Without loss of hydraulic fluid from the cylinder.

The piston section I9 is provided with a concentric tubular guide 22 -which reciprocates through a packing gland 23 at the opposite end of the cylinder, and which carries a coil spring 24 bea-ring against a pin 2-5. This spring normally urges the piston toward the inner end of the cylindera movement which shortens the overall assembly, and moves the seat back forward, as will be later understood. j

The piston section I3 carries a packing ring 26 which seals against the cylinder wall, and an internal packing ring 2l which seals against the outer surface of areciprocable valve 2B. which has a stem 29 which projects from the end of the hollow piston rod 2i). The piston is provided with open by-pass passages 33 and 3l, and a valve Controlled fluid flow passage 32. As will be seen, the innerend of the valve 28 has a short central bore which houses a spring 33 bearing against a ball 34 to normally keep the ball seated on a valve seat insert 35.V The cylindrical valve 28 is slightly smaller in diameter than the bore of the'piston rod in which the valve reciprocates, but the sealing ring 21 seals closely about the valve. A perforation 36 affords communication between the space surrounding the valve and the bore in its end. The outer surface of this valve is provided with one or more longitudinally disposed grooves 37 which permit hydraulic Iiuid to flowl beneath the sealing ring when the valve moves'into the passage 3l in the piston, the complete operation being explained more fully hereinafter.

The means of mounting the forward end of this hydraulic assembly on the seat includes a trunnion 40 the ends of which are rotatably mounted in the upper end of a post 4i, and terminate in projecting pins 42 and 43. Intermediate its ends the trunnion is cross bored and threadly receives the outer end of the piston rod 25, iwhich passes through an oversized perforation 44 in the wall of the post 4 I. An oppositely positioned oversized perforation 45 in the post wall loosely receives the valve stem 29. Mounted on the valve stem 29 outside the post 4I is a spacer 46, a spring 4l, and a knob or valve operating button 48, the spring serving to normally urge the valve toward-a closed position, as shown in Figure 1. The oversized perforations 44 and 45 permit the piston and cylinder assembly to pivot slightly about the trunnion 4t during adjustment of the seat back.

At is lower end the post 4l is provided with oppcsitely positioned goose neck slots 49 which cooperate with a cross pin 50 carried internally by the arm supports II and I2 near their upper ends, to removably anchor each post within the upper end of its upright. A slight turn of the entire assembly allows removal of the post 4I from its arm support.

Operation into the space surrounding the valve 28, and into the chamber 5I through the port 32. This would result in the piston slowly approaching the gland 23, and in an overall shortening of the entire assembly. This in turn would cause the seat back to assume a more upright position. If the invention was installed on grouped seats as in a bus, railroad car, or the like, the back rests of all unoccupied seats would thus present a uniform appearance.

With the back rest in its farthest forward position, a seat occupant who wishes to increase the angle of inclination of the back rest simply pushes inward on the button 48. The valve 28 is thus moved partially into the chamber 3I. and the groove 3i passes beneath the sealing ring 2l. A slight rearward pressure on the back rest then causes liquid to flow from chamber 5i through port 32 into the space surrounding the valve Z8, through the groove 3l beneath the sealing ring 2l', and directly into the chamber 3i. During this fluid flow the back rest is permitted to pivot rearward. When the back rest has assumed the desired position, the seat occupant releases the knob, and the valve 28 is returned to the position shown in Figure 1, stopping all fluid ow from chamber 5I into chamber 3|. The normal pressure of the occupants back on the back rest is greater than the pressure of spring 24, and this hydraulic unit thus holds the back rest in the set position. f l

By leaning forward in the seat and pressing the knob 48, fluid is allowed to flow quickly from chamber 3l into chamber 5I under the urgence of spring 24, and the back rest quickly assumes its full forward position.

.As a means of housing the unit within the upholstered arm rest Eil of a seat, I utilize the pins 42 and 43 which projects from the opposite ends of the trunnion 4B, and two identical pins 53 suitably mounted on the housing section I'I, and projecting outwardly therefrom in a substantially horizontal plane. A shell 54, open along its bottom and at its ends, carries an internally mounted spring clip 55 the two free ends of which are perforated, as shown, to receive the pins 42 and 43 of the trunnion 4o. Near its rear end the shell is provided with internally mounted guide brackets 5B and 5'I, which are provided with facing substantially horizontal grooves which slidably receive the pins 53. The arm rest padding and its outer fabric covering are mounted directly on the shell 54, so that it forms a unitary removable housing for the back rest holding unit. The aft end of the arm rest is simply placed over the unit I5, and the pins 53 slide into the grooves in the brackets 56 and 5l. The ends of the spring clip 55 are then sprung outwardly until the pins 42 and 43 enter the perforations. The arm is thus anchored in proper position, yet it does not in any way interfere with the movement of the cylinder I5 as the hydraulic unit I5 elongates. The pins 53 simply move along the grooves in the guide brackets.

Having described the invention with sufficient clarity to enable those familiar with the art to construct, assemble, and use it, I claim:

l. A seat comprising in combination: A supe ported seat base; an arm support rigidly connected to the base and having a socket therein; a back rest pivotally connected to the seat base; an extensible hydraulic piston and cylinder unit for controlling the tilting of the back rest; a post pivotally connected to one end of said unit and adapted to seat removably in the socket of the arm support; removable means `pivot/ally connecting the other end of said unit to the back rest; and means for controlling the elongation and contraction of the unit.

2. The organization described in claim 1, and a removable arm rest housing said hydraulic unit.

3. The invention described in claim 1 and a hollow arm rest removably housing the hydraulic unit and supported thereby independent of any contact with the seat proper.

4. The invention described in claim 1 in which the said means for controllingr the elongation and contraction of the hydraulic unit is in the form of an outwardly spring pressed reciprocable rod which projects forwardly through said post.

HARRY M. MCFADDEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 85,481 Schmitt Dec. 29, 1868 1,950,226 Cable Mar. 6, 1934 1,970,480 Wood Aug. 14, 1934 1,991,676 Huwyler Feb. 19, 1935 2,090,311 Saltman Aug. 17, 1937 2,201,261 Frey May 21, 1940 2,248,487 Booth July 8, 1941 2,354,889 Smith Aug. 1, 1944 2,419,412 McArthur Apr. 22, 1947 FOREIGN PATENTS Number Country Date 268,840 Germany Feb. 14, 1913 

